The use of containers of pressurised fluid, aerosol canisters, to spray fluids of various natures are commonplace in both domestic and commercial environments. Whilst the spraying of some fluids are required on “as required” basis, such as spraying a cleaning fluid on to a surface requiring cleaning, many other fluids could usefully be sprayed into the localised environment routinely to provide a constant background benefit. For instance, the routine spraying of air freshening compositions may be desirous to ensure that a room has a near constant level of fragrance for the users of the room to experience, similarly the routine spraying of pest control compositions may be desirous to ensure has a near constant level protection against pests such as airborne insects and the like.
Early efforts to provide an automatic spraying device can be seen in U.S. Pat. No. 3,968,905 published in July 1976 in which a mechanical mechanism is proposed which essentially relies on the inherent resilience of a spring disk to close an exit orifice for a period of time on exposure to the pressurised fluid of the aerosol canister. It is alleged that eventually the fluid pressure beneath the disk will become sufficient to overcome the resistance of the concave disk snapping it into a convex formation thus allowing the fluid to flow past the disk and out of the exit orifice before the inherent resilience of the disk overcomes the pressure of the fluid passing around it to snap back into a concave formation to start the cycle again. The present inventors are not aware of this device, or a device similar thereto ever being commercialised and it is assumed that this is due to the described arrangement being theoretical and that in practice such a device would never work since finding a disk having the required properties does not exist. For instance, despite the presence of the flow restrictor the disk would be exposed immediately or at least very quickly to the full pressure of the aerosol container such that should the disk be forced into the convex formation it is not understood why the disk would then snap back to the concave formation before all of the contents of the aerosol canister had bypassed the disk. Furthermore, since the pressure of the fluid in the canister would decrease over time it is not understood how a disk could be operable with the varying pressures it would be exposed to as the fluid became increasingly depleted. Although US'905 refers to preliminary performance results these value are merely theoretical based on a desired dosage size and time interval of sprays.
To address the need for automatic spraying devices numerous electrically powered device became available. One typical device is battery operated and provides a motorised actuator arm and a timer in a control unit to routinely activate the arm which contacts a valve actuator on the aerosol to depress same to open the valve and cause the pressurised fluid to be sprayed. An alternative device does not provide a valve actuator, rather the aerosol is loaded into the device and the action of loading opens the valve exposing the device to the full pressure of the fluid therein. The routine spraying is achieved by the device using a solenoid switch to open a valve in the device for a short period of time thus permitting a small quantity of the fluid to be released in accordance with a timer in a control unit.
Unfortunately there are drawbacks associated with the currently available electrically powered automatic spraying devices is that they are expensive to manufacture due to the raw materials required including the microchips in the control units, electrical wiring, motors, solenoid switches, sufficient housing material to encapsulate the aerosol canister within the interior of the device. Also from a user perspective these devices can be inconvenient in that they require batteries to operate, their size can be considered cumbersome, due to their cost they cannot be considered as disposable, the canister is typically obscured when engaged with the device.
It is an object of the present invention to provide a non-electrically powered automatic spraying device which will address such drawbacks whilst also being manufacturable rather than representing a mere theoretical solution.